This invention concerns a method for managing fuel consumption of a hybrid vehicle on a given trip, in order to optimize energy savings on such a trip. The invention also concerns a vehicle adapted to perform such a method.
The reduction of fuel consumption of automotive vehicles, in particular trucks, is a major issue for the sustainability of road transport and is a key element for the competitiveness of truck manufacturers.
In order to optimize fuel consumption of an internal combustion engine of a vehicle, it is known, e.g. from U.S. Pat. No. 7,240,750, to take into account future energy needs in a hybrid vehicle in order to pro-actively charge the vehicle battery to an appropriate level. Such an approach does not take into account the behaviour of the driver.
It is also known from JP-A-11 220 807 to compute, on the basis of the running state of a vehicle or the behaviour of a driver, a reference fuel consumption and to display an instantaneous actual fuel consumption and the reference fuel consumption. This comparative display is not connected to the actual trip being traveled through by the vehicle, so that optimization of the energy needs is not fully effective.
This invention, according to an aspect thereof, aims at proposing a new method for managing fuel consumption of a hybrid vehicle on a given trip, this method being such that the energy savings resulting from the use of the hybrid components of the vehicle, which derive in particular from the behaviour of the driver, can be compared to a target or optimized value which can be determined on the basis of the trip to be traveled through and on the features of the vehicle.
With this respect, the invention, according to an aspect thereof, relates to a method for managing fuel consumption of a hybrid vehicle on a given trip, this vehicle comprising an internal combustion engine, electric energy storage means and at least an electric machine adapted to work as a generator or as a motor. This method comprises at least the following steps:                a) determination, for the given trip, of a target value of a parameter representative of fuel economy resulting from the use of the electric machine,        b) determination of an actual value of this parameter when the vehicle is running on the given trip,        c) comparison of the target value and actual value determined here-above, and        d) information of a user of the result of the comparison, at least at the end of the trip.        
The actual value of the parameter depends on the driving style or behaviour of the driver. Thanks to an aspect of the invention, the driver or a fleet manager can be kept informed of the influence of the driver's style and/or behaviour onto the efficiency of the energy savings resulting from the use of the hybrid components of the vehicle. In other words, the driver and/or the fleet manager is/are aware of the influence of the driving style on the fuel savings for the given trip.
According to a first embodiment of an aspect of the invention, step a) includes at least the following sub-steps:                a1) performance of at least a trial run on the given trip with the vehicle and recordal of a dataset of the vehicle on this trial run,        a2) computation, on the basis of at least the dataset, of a first energy needs value of the vehicle to travel the given trip when only an internal combustion engine is used,        a3) computation, on the basis of at least the dataset, of a second energy needs value of the vehicle to travel the trip when the internal combustion engine, the storage means and the electric machine are used, and        a4) computation of a target value of the parameter, on the basis of the first and second energy needs values.        
In such a case, the dataset recorded in step a1) is advantageously representative of the trip and of the operation of the vehicle on the trip. This dataset can include at least a velocity profile of the vehicle along the trip.
Alternatively, and according to another embodiment of an aspect of the invention, step a) includes at least the following steps:                a′1) generation of a model of the trip and the vehicle,        a′2) computation, on the basis of the model, of a first energy needs value of the vehicle to travel the given trip when only an internal combustion engine is used,        a′3) computation, on the basis of the model, of a second energy needs value of the vehicle to travel the trip when the internal combustion engine, the storage means and the electric machine are used, and        a′4) computation of a target value of the parameter, on the basis of the first and second energy needs values.        
According to further aspects of an aspect of the invention which are advantageous but not compulsory, this method can incorporate one or several of the following features:                steps a2) to a4) or a′2) to a′4) take place in an off-board computer;        the target value is stored onboard the vehicle after it has been determined;        step b) is performed onboard of the vehicle, on the basis of the actual working conditions of the internal combustion engine, the storage means and the electric machine, when the vehicle is running on the given trip;        step c) is performed onboard of the vehicle and, in step d), the driver is informed onboard of the result of the comparison;        step d) can take place at the end of the trip or occur several times or continuously when the vehicle is running on the given trip,        alternatively or in addition, in step d), information is sent to a remote computer (202) with respect to the result of the comparison of step c).        the parameter which represents fuel economy is a ratio of the energy needs of the vehicle for the given trip which corresponds to the energy savings resulting from the use of the storage means and the electric machine.        
The invention, according to an aspect thereof, also concerns a hybrid automotive vehicle which is adapted to perform the method mentioned here-above. This vehicle comprises an internal combustion engine, electric energy storage means, at least an electric machine adapted to work as a generator or as a motor, a memory adapted to store the target value, computation means adapted to determine the actual value of the parameter and to make the comparison of step c) and display means adapted to allow information of the driver according to step d).
The display means are advantageously adapted to display graphically a ratio of the actual value to the target value of the parameter representative of fuel economy.